<p>The authors argue that a simple alternative to copying as a data movement primitive-swapping (exchanging) the values of two variables-has potentially significant advantages in the context of the design of generic reusable software components. Specifically, the authors claim that generic module designs based on a swapping style are superior to designs based on copying, both in terms of execution-time efficiency and with respect to the likelihood of correctness of client programs and module implementations. Furthermore, designs based on swapping are more reusable than traditional designs. Specific arguments and examples to support these positions are presented.</p>